Printers, photocopiers, facsimile machines, and other electronic printing devices all employ media handling systems to guide media from an input source to an output destination. Familiar types of media include paper, labels, and transparencies. The media can be produced in different forms. For instance, paper can be produced as a continuous roll, with perforations defining pages for separation after printing. Alternatively, paper can be manufactured as stacks of separate sheets which are fed individually into the device prior to printing. Media handling systems often vary in design depending upon the form of the media (e.g., continuous or individual sheets).
To handle individual sheets, a media handling system typically include a media separation system to separate individual sheets from the stack of sheets for input to the printing device. The media separation system enables automatic sheet feeding whereby individual sheets are supplied one at a time from a bin or container that holds a stack of sheets to the printing device.
The ability to efficiently and repeatedly separate a single sheet from a stack of like media is a difficult design task. This difficulty is magnified when you consider that the stack is always changing in thickness, as sheets are used or replenished. As a result, conventional media separation systems are often technically sophisticated and employ a large number of parts, thereby increasing costs to the overall printing device.
There is a trend toward making printing devices smaller, lighter weight, and portable. As part of this trend, there is a need to devise media separation systems that employ fewer parts, with less moving components, and which are less expensive.